1. Field of the Invention
The present invention relates to a power on/off control device for a personal computer, specifically relates to a power on/off control device for computer capable of preventing a loss of data being in process, due to a sudden power-off caused by making a mistake of operating.
2. Discussion of Related Art
As computer techniques have been developed rapidly, especially in terms of function and speed for processing, a personal computer is widely being used as a communication terminal, and being developed to use as a central equipment for a home automation, whereas the conventional personal computer has been used simply as a word processor or as a data processor.
As the conventional computer is turned on and turned off only by operating of a mechanical power switch, it cannot accommodate with various user environments and, in fact, data being processed used to be lost by making a mistake of operating a power switch in the middle of working.
Thus, the applicant of the present invention has proposed a power on/off control device for computer for controlling the power on/off of a computer, especially controlling the power-off by operating a software function.
FIG. 1 shows a configuration of the power on/off control device for computer, disclosed in U.S. patent application Ser. No. 08/749,027. In the figure, reference numeral 1 denotes a power plug, numeral 2 a standby power source for outputting standby power Vs:5V needed when standby mode, based on input power from the power plug 1, and number 3 a switching mode power supply (SMPS), operated according to power control signal PWR+L received from a RTC 4, hereinafter described, for generating variable operating voltages V1 to V4, based on the input power from the power plug 1.
And reference symbol SW1 denotes an on/off switch, installed outside the computer, for turning a computer on and off mechanically by user, of which one end is grounded and the other end is connected to one end of an AND gate AND1 through a pull-up resistor R1. And the other end of the AND gate AND1 is connected with an infrared receiver, not depicted.
Here, the infrared receiver, which is a usual one for turning on and off a computer by receiving user's infrared command through a remote controller, outputs, for example, low level signal for a predetermined time, if a user inputs infrared signal to turn on the computer through the remote controller. That is, the AND gate AND1 outputs power-on signal of low level for a corresponding time, while the user is operating the remote controller or the on/off switch SW1 to turn on the computer.
Reference numeral 4 denotes a real time clock RTC, in which a kick start signal input port KS+L receives the output of the AND gate AND1 and a kick start signal output port PWR+L is connected to the SMPS 3 through a pull-up resistor R2. And the RTC 4 outputs power control signal of low level through the output port PWR+L at a falling edge of corresponding signals, for example, for a couple of seconds, when the signal inputted from the kick start signal input port KS+L turns to be low level, and then outputs power control signal of low level through the output port PWR+L till the output port PWR+L is set to high level by means of another power-off operation, that is, data obtained from a system data bus, when a normal voltage of +5V is outputted from the SMPS 3 which is operated normally by the power control signal of low level from the output port PWR.
Besides, the RTC 4, including a status resistor, not depicted, for setting signal status inputted from the kick start signal input port KS+L , sets a status flag, for example, to "1" at a falling edge of the signal inputted through the kick start signal input port KS+L , the status flag can be read and reset through a system address bus and a system data bus.
Meantime, when the computer is turned on, a CPU, not depicted, resets the status flag "1" to "0", stored at the status resistor of the RTC 4, through the system address bus and the system data bus, and then detects whether the status flag is reset to "1". When the status flag is set to "1" again, the system data bus and the system address bus set the output of power control signal PWR+L of the RTC 4 to high level, thus suspending the operation of the SMPS 3. That is, in the above configuration, the power-off operation of the computer can be controlled by the CPU.
Accordingly, the above configuration provides various user environments, that is, confirming user's intention to turn off a computer when the user touches power switch, turning off the computer automatically after the computer remains alone for a predetermined time, and so on.
Meantime, as the power on/off control device for computer described above is designed to be turned off only by the CPU, it comes to be a problem that the computer can not be turned off through the power switch, in case that the CPU doesn't work by reason that the system is down, and so on.